Usart1 BRR register seems strange when using STM32H743 with stm32cubeh7 1.12.1

[zsk]

Dear all,

    I have encountered an strange issue. I set Usart1 Baud Rate to 115200, however, Usart1 BRR[15:4]==0x0082, which corresponds to 57600.(57600 == 120Mhz/(16*0x82)). 

  I also noticed that HAL_RCC_GetPCLK2Freq() returns a wrong pclk value 0x0E4E1C00(240M), but it should be 120M.

The Usart1 Config and Rcc config are as follows :

[TDK · Accepted solution]

This has been an issue in the past. Is your STM32H7 package fully updated? If so, can you include your IOC file here?

The relevant fix was made 4 months ago. (Might not be this exact change.)

[Pavel A.]

> The relevant fix was made 4 months ago

This line with D1CorePrescalerTable array has not been changed recently. 

[zsk]

I am sure it's the lastest version 1.12.1. But the details remain the same as 1.12.0. I guess the 1.12.1 release missed this problem.

[Pavel A.]

Can you compare the generated code, especially for SystemClock_Config?

[TDK]

Works for me on a new project, updated tools. Nucleo H743 board. USART1.

  printf("HAL_RCC_GetHCLKFreq() = %u\n", (unsigned)HAL_RCC_GetHCLKFreq());
  printf("HAL_RCC_GetPCLK2Freq() = %u\n", (unsigned)HAL_RCC_GetPCLK2Freq());
  printf("USART1->BRR = %u\n", (unsigned)USART1->BRR);
  printf("baud = %.6g\n", (unsigned)HAL_RCC_GetPCLK2Freq() / (float)USART1->BRR);
  printf("main loop started!\n");

Output:

HAL_RCC_GetHCLKFreq() = 240000000
HAL_RCC_GetPCLK2Freq() = 120000000
USART1->BRR = 1042
baud = 115163